The subject line says all. Is there a way to create/modify a bitmap
image on screen pixelwise?

Until now I've only found the possibility to redraw the whole image
after individual pixel changes.

Thanks in advance.
--
Manuel Collado - http://mcollado.z15.es

Am 07.11.2023 um 11:09 schrieb Manuel Collado:
> The subject line says all. Is there a way to create/modify a bitmap
> image on screen pixelwise?
>
> Until now I've only found the possibility to redraw the whole image
> after individual pixel changes.
>
> Thanks in advance.

Yes, there is.

https://www.tcl-lang.org/man/tcl8.6/TkCmd/photo.htm#M30

You will need Tk 8.7 to manipulate the full alpha channel.

Enjoy,
Harald

El 7/11/23 a las 11:55, Harald Oehlmann escribió:
> Am 07.11.2023 um 11:09 schrieb Manuel Collado:
>> The subject line says all. Is there a way to create/modify a bitmap
>> image on screen pixelwise?
>>
>> Until now I've only found the possibility to redraw the whole image
>> after individual pixel changes.
>>
>> Thanks in advance.
>
> Yes, there is.
>
> https://www.tcl-lang.org/man/tcl8.6/TkCmd/photo.htm#M30
>
> You will need Tk 8.7 to manipulate the full alpha channel.

Sorry for not being clear enough. Subject updated. I'm working on bitmap
images. The 'put' image command seems to be only available for photos.

Anyway thanks for your hint. Perhaps I should consider using photos
instead of bitmaps.

--
Manuel Collado - http://mcollado.z15.es

On 2023-11-08, Manuel Collado <mcollado2011@gmail.com> wrote:
> El 7/11/23 a las 11:55, Harald Oehlmann escribi??:
>> Am 07.11.2023 um 11:09 schrieb Manuel Collado:
>>> The subject line says all. Is there a way to create/modify a bitmap
>>> image on screen pixelwise?
>>>
>>> Until now I've only found the possibility to redraw the whole image
>>> after individual pixel changes.
>>>
>>> Thanks in advance.
>>
>> Yes, there is.
>>
>> https://www.tcl-lang.org/man/tcl8.6/TkCmd/photo.htm#M30
>>
>> You will need Tk 8.7 to manipulate the full alpha channel.
>
> Sorry for not being clear enough. Subject updated. I'm working on bitmap
> images. The 'put' image command seems to be only available for photos.
>
> Anyway thanks for your hint. Perhaps I should consider using photos
> instead of bitmaps.

Sorry is there a difference? A photo is an image and both are displayed
as some form of bitmap.

Surely if you have some image decoded in memory as a bitmap, it is just
some sort of array or values, probably 24 bit RGB values. All you do is
alter the number sin the array with your new numbers, and pass altered
array for display. Or are you wanting to actually alter the numbers in
the buffer on the memory card?

Jim Jackson <jj@franjam.org.uk> wrote:
> On 2023-11-08, Manuel Collado <mcollado2011@gmail.com> wrote:
>> El 7/11/23 a las 11:55, Harald Oehlmann escribi??:
>>> Am 07.11.2023 um 11:09 schrieb Manuel Collado:
>>>> The subject line says all. Is there a way to create/modify a bitmap
>>>> image on screen pixelwise?
>>
>> ...
>>
>> Anyway thanks for your hint. Perhaps I should consider using photos
>> instead of bitmaps.
>
> Sorry is there a difference? A photo is an image and both are displayed
> as some form of bitmap.

From the perspective of the image data, no.

For Tcl, it defines two different "image types":

man n image:

BUILT-IN IMAGE TYPES
The following image types are defined by Tk so they will be
available in any Tk application. Individual applications or
extensions may define additional types.

bitmap Each pixel in the image displays a foreground color, a
back‐ground color, or nothing. See the bitmap manual
entry for more information.

photo Displays a variety of full-color images, using dithering to ap‐
proximate colors on displays with limited color
capabilities. See the photo manual entry for more
information.

And the available Tcl sub-commands for manipulating the two different
types of images are different.

On 2023-11-08, Rich <rich@example.invalid> wrote:
> Jim Jackson <jj@franjam.org.uk> wrote:
>> On 2023-11-08, Manuel Collado <mcollado2011@gmail.com> wrote:
>>> El 7/11/23 a las 11:55, Harald Oehlmann escribi??:
>>>> Am 07.11.2023 um 11:09 schrieb Manuel Collado:
>>>>> The subject line says all. Is there a way to create/modify a bitmap
>>>>> image on screen pixelwise?
>>>
>>> ...
>>>
>>> Anyway thanks for your hint. Perhaps I should consider using photos
>>> instead of bitmaps.
>>
>> Sorry is there a difference? A photo is an image and both are displayed
>> as some form of bitmap.
>
> From the perspective of the image data, no.
>
> For Tcl, it defines two different "image types":
>
> man n image:
>
> BUILT-IN IMAGE TYPES
> The following image types are defined by Tk so they will be
> available in any Tk application. Individual applications or
> extensions may define additional types.
>
> bitmap Each pixel in the image displays a foreground color, a
> back???ground color, or nothing. See the bitmap manual
> entry for more information.
>
> photo Displays a variety of full-color images, using dithering to ap???
> proximate colors on displays with limited color
> capabilities. See the photo manual entry for more
> information.
>
> And the available Tcl sub-commands for manipulating the two different
> types of images are different.
>

On Thursday, November 9, 2023 at 5:06:52 AM UTC-8, Jim Jackson wrote:
> On 2023-11-08, Rich <ri...@example.invalid> wrote:
> > Jim Jackson <j...@franjam.org.uk> wrote:
> >> On 2023-11-08, Manuel Collado <mcolla...@gmail.com> wrote:
> >>> El 7/11/23 a las 11:55, Harald Oehlmann escribi??:
> >>>> Am 07.11.2023 um 11:09 schrieb Manuel Collado:
> >>>>> The subject line says all. Is there a way to create/modify a bitmap
> >>>>> image on screen pixelwise?
> >>>
> >>> ...
> >>>
> >>> Anyway thanks for your hint. Perhaps I should consider using photos
> >>> instead of bitmaps.
> >>
> >> Sorry is there a difference? A photo is an image and both are displayed
> >> as some form of bitmap.
> >
> > From the perspective of the image data, no.
> >
> > For Tcl, it defines two different "image types":
> >
> > man n image:
> >
> > BUILT-IN IMAGE TYPES
> > The following image types are defined by Tk so they will be
> > available in any Tk application. Individual applications or
> > extensions may define additional types.
> >
> > bitmap Each pixel in the image displays a foreground color, a
> > back???ground color, or nothing. See the bitmap manual
> > entry for more information.
> >
> > photo Displays a variety of full-color images, using dithering to ap???
> > proximate colors on displays with limited color
> > capabilities. See the photo manual entry for more
> > information.
> >
> > And the available Tcl sub-commands for manipulating the two different
> > types of images are different.
> >

For bitmaps, you can define the image via a string.
To modify the image, modify the original string, then do a configure -data on the image to update the view.

#
# See Wikipedia for xbm description: https://en.wikipedia.org/wiki/X_BitMap
#

set data {#define test_width 16
#define test_height 7
static unsigned char test_bits[] = {
0x13, 0x00, 0x15, 0x00, 0x93, 0xcd, 0x55, 0xa5, 0x93, 0xc5, 0x00, 0x80,
0x00, 0x60 };}

set img [image create bitmap -data $data]
label .l2 -image $img
pack .l2

regsub {0x00} $data {0xff} d2
$img configure -data $d2

-Brian